Heart valve replacement may be indicated when there is a narrowing of a native heart valve or when the native valve leaks or regurgitates, such as when the valve's leaflets are calcified.
The native valve can be excised and replaced with either a biologic tissue valve or a mechanical valve. Mechanical valves require lifelong anticoagulant medication to prevent blood clot formation, and clicking of the valve can often be heard through a patient's chest. Biologic tissue valves typically do not require such medication and do not click. Tissue valves can be obtained from cadavers or can be porcine or bovine based, and the valves can be attached to cloth-covered synthetic rings or leaflet support frames that are securable to a patient's heart valve annulus.
Conventional heart valve surgery is an open heart procedure conducted under general anesthesia with significant concomitant risks, including bleeding, infection, stroke, heart attack, arrhythmia, renal failure, adverse reactions to the anesthesia medications, or sudden death. An incision is made through the patient's sternum, and the patient's heart is stopped while blood flow is rerouted through a heart-lung bypass machine. The first two or three days following conventional heart valve surgery are often spent in an intensive care unit where heart functions can be closely monitored. The average hospital stay following conventional heart valve surgery is between one and two weeks, with several more weeks required for complete recovery.
Advancements in minimally-invasive surgery and interventional cardiology have encouraged some physicians to pursue percutaneous replacement of a heart valve, including the deployment of an expandable prosthetic heart valve device across the native diseased heart valve (which permanently holds the native valve open). The prosthetic heart valve device can be designed for percutaneous delivery in a cardiac catheterization laboratory under local anesthesia using fluoroscopic guidance, thereby avoiding general anesthesia and open-heart surgery.